Apparatus for crimping fibers



Nov. 23, 1965 w. H. HENDRIX 3,218,675

APPARATUS FOR CRIMPING FIBERS Filed June 27, 1965 24 2a if; 2

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INVENTOR WALTER H. HENomx BY N/QQMA/ ATTORNEY United States PatentOffice 3,218,675 Patented Nov.` 23, 1965 3,218,675 APPARATUS FORCRIMPING FIBERS Walter H. Hendrix, Lugoff, S.C., assignor to E. I. duPont de Nemours and Company, Wilmington, Del., a corporation of DelawareFiled June 27, 1963, Ser. No. 291,069 3 Claims. (Cl. 19-66) Thisinvention relates to apparatus for mechanically crimping syntheticfilamentary tow.

The need for crimp in commercial textile processing of fibers intostaple yarns is well established. Since most synthetic filaments havelittle or no tendency to crimp as produced, it is necessary to impartcrimp mechanically in the manufacturing process, using, for example, thestufling-box crimper such as described tin U.S. Patents 2,311,174 and2,747,233, or some variant thereof.

It has long been recognized in the art that mechanical crimping leads todegradation of phyical properties of synthetic filaments. Propertiessuch as fiber tenacity and elongation, both of which are important totextile processability and to broadest utility of fabrics madetherefrom, are adversely affected by crimping. Furthermore, the tendencyof most synthetic fibers to lose mechanically-induced -crimp which isimparted without benefit of heat setting, imposes severe demands oninitial crimp intensity to compensate for this loss. The development ofcrimp of initially high intensity in commercial rate processes, hasrequired that the crimping process be operated in a critical performancearea wherein minor process variations can lead to severe productproperty degradation. The criticality of this operation is furtherexaggerated by demand for increased speed of production.

It has now been found that non-uniformity in distribution of filamentsas the tow enters the bite of the crimper stuffing rolls is a majorcause for mechanical degradation of filaments when crimping undercritical conditions of high speed and high crimp intensity. In extremecases, near-fushion of filaments into agglomerations which are notreadily opened by normal textile processing, as well as gross filamentrupture, may occur. Such damaged tow -is unsuitable for commercialtextile use.

It is the primary object of this invention to provide apparatus foruniformly crimping filamentary tow. It is a more specific object of thisinvention to provide improved apparatus which can be operated at highspeeds to crimp tow with a minimum of mechanical damage to thefilaments. Other objects ill become apparent from the detaileddescription which follows.

The objects of this invention are achieved by providing in tow crimpingapparatus which includes cooperating rolls which form a nip foradvancing a tow and a crimping chamber below the rolls for receiving andrestricting the advance of the tow, a pair of stationary flanged spoolguides adjacent to and in advance of the rolls. The guides have theirmajor axes parallel to the nip formed by the rolls and are aligned instaggered relationship along the axial path of advance of the tow tocontact opposite surfaces of the tow and deflect it from its normalaxial path as it passes between the guides to the rolls. Surprisingly,by dellecting the tow from about 5 to 22 from its normal course oftravel as it passes between the spool guides, the filaments in the towbecome oriented in a uniform pattern as they enter the bite of the feedrolls with the crimped filaments issuing from the stufling-box showinglittle, if any, damage.

For a detailed description of the invention in its preferred form,reference is made to the accompanying drawings wherein? FIGURE 1 is adiagrammatic sketch of the apparatus;

FIGURE 2 is a d-iagrammatic vertical sectional view of the apparatustaken along line 2-2 of FIGURE 1, and FIGURES 3 and 4 are fragmentarysectional views of the flange and adjoining barrel portions ofembodiments of the spool guides shown in FIGURE l.

With reference to FIGURE l, two feed rolls 12 and 14 having smoothcylindrical peripheral surfaces are mounted in opposed relationship toengage and forcibly feed a flamentary tow 16 into crimping chamber 1S.Mounted immediately above rolls 12 and 14 are flanged spool guides 20and 22 with the inner surfaces of their respective flanges 24, 24 and26, 26 substantially aligned with the vertical sides of rolls 12 andl14. Spool guides 20 and 22 are fixedly positioned in a staggeredrelationship with respect to the normal course of travel of tow 16 andare mounted on arms 28 and 30 of frame 32.

In operation tow 16 is passed from a source not shown between theflanges 24, 24 and 26, 26 and in contact with the peripheral surfaces ofspool guides 20 and 22 when the lateral edges of the tow are aligned andthe path of travel is slightly changed. -As the tow cornes into contactwith the surfaces of the spool guides 20 and 22, the deflection andContact with the surfaces causes the individual filament to becomealigned in a uniform pattern. The tow is then engaged by feed rolls 12and 14 and forced into crimping chamber 18. As illustrated in FIGURES land 2 of the drawing, the tow is confined in the crimping chamber byshoe plates 11 and 13 and by front and back plates 15 and 17. The frontand back plates 15 and 17 have their inner surfaces in adjacent parallelrelationship with the peripheral surfaces of rolls 12 and 14 forrestricting the lateral passage of the tow between the rolls. Pressuremay be applied through openings 19 and 21 to inserts 23 and 25 toprevent lateral emergence of Ifilaments from the nip of the rolls.Crimping of the filaments is accomplished by the action of a clapperplate positioned near the base of the crimping chamber, not shown, whichrestricts the rate at which the filaments are permitted to pass throughchamber 18.

The configuration of the flanged spool guides may be varied to achievevarious effects. While a smooth barrel 34, shown in FIGURE 3, providesgreater freedom for filament distribution between flanges 24, 24' and26, 26', a grooved barrel 36, as shown in FIGURE 4, may be used to forcecross-flow of filaments from heavy areas in the tow to the thinnerareas. In a preferred embodiment, the barrel portion has a corrugatedconfiguration with the grooves -being spaced from about 0.1 to 0.12 inchapart and being from about 0.025 to 0.035 inch deep. The taperedentrance to the surface of the barrel which is provided by the flangesaccomplishes a foldover of the thin edges which are always present in arunning tow. The tow is preferably adjusted to a total width slightlygreater than the distance between the flanges by use of conventionalspreading or contracting parabolic guides at a point upstream from theflanged spool guides.

The benefit of the flanged spool guides to crimping uniformity andthereby to product quality is substantial. Uniformity of crimp and oftow quality heretofore unobtainable is regularly obtained with theapparatus of this invention. As shown previously, a major factor insatisfactory processability of a multi-filament tow is intimateinterlacing of adjacent filaments so as to permit handling of the entirebundle as a consolidated ribbon. Without interlacing at all points alongits length, the tow may split which prevents the filament interactionnecessary to broadening, narrowing, and uniformizing filamentdistribution in the tow structure by means of, for example, convex orconcave parabolic guides.

A test procedure for evaluating splitting which has been devised takesinto consideration not only the frequency of splits but also theirlength. A split which is from barely apparent to yards in length isgraded as a 2 point split. One which has a length of 6 to 11 yards isassigned a value of 4 points. Those which are 12 yards -or longer areassigned a value of 6` points. With this rating in mind, the comparisonsof the test described below can more readily be understood. All ratingsare based on 100 lbs. of tow.

A test wherein this invention was compared with a previous process whichemployed finger guides to control only the lateral position of the towat each edge thereof demonstrated striking improvement in a critical towquality characteristic. In this test, several hundred pounds of 3 denierper filament tow, having a total denier of 470,000, made by each processwere run on a Turbo Stapler which is commonly used in the textile tradeto break tow to staple. The quality of the entering tow and the emergingsliver were monitored visually throughout the test. Tow made using theapparatus of this invention had 5.6 degradation points for splits whilethe tow made by use of the finger guides showed 102 points. A splitoccurs due to failure of the crimping process to interlace the filamentsproperly. It is not possible to maintain a uniform distribution of feedto the Turbo Stapler in the area of a split, and a sliver defect knownas a slub may develop. A slub results from exactly parallel breaks in agroup of filaments and generally occurs in a thick area -of the towcross section. Since each filament in a slub is presented simultaneouslyto drafting rolls in succeeding steps of textile processing, they willnot be drafted properly and will lead to a defect in the final yarn. Inthis test, less than half as many slubs were observed in the productmade using the apparatus of this invention as were observed in theproduct made using the linger guides.y

In another test, the inliuence of the lianged spool guide on maximumspeed of crimper operation without tow defects was determined. With thefinger guides for control of the edges of the tow as it enters the biteof the stufing rolls, a maximum of 300 yards per minute processingwithout easily observable degradation in the crimped tow was found. Withthe apparatus and process of this invention, extended runs at 360 yardsper minute were made without tow degradation, and short tests have shownspeeds as high as 400 yards per minute to be feasible.

Since various embodiments of this invention will become apparent tothose skilled in the art, the invention is not to be limited by thespecific embodiment disclosed herein except as set forth in the appendedclaims.

I claim:

1. In tow -crimping apparatus which includes cooperating rolls whichform a nip for advancing a tow, a crimping chamber below said rolls forreceiving and restricting the advance of said tow, and a pair of opposedplate members having the inner surfaces in adjacent parallelrelationship with the peripheral surfaces of said rolls for restrictingthe lateral passage of said tow between said rolls: a pair of stationaryflanged spool guides adjacent to and in advance of said rolls, saidspool guides having their major axes parallel to the nip formed by saidrolls, the fianges of said guides having inwardly tapering surfaces withthe bases of said flanges being in a plane essentially parallel to andin alignment with the lateral surfaces of said rolls, said guides beingarranged in staggered relationship with the axial path of advance ofsaid tow to contact opposite surfaces of said tow and defiect it fromits normal axial path as it passes between said guides to said rolls.

2. The apparatus of claim 1 wherein said flanges have inwardly taperingsurfaces at their extremities and essentially straight portions adjacentthe base of said ange.

3. The apparatus of claim 2 wherein the surface between the `flanges ofsaid guides has a corrugated configuration consisting of annular groovesand ridges.

References Cited by the Examiner UNITED STATES PATENTS 1,893,809 1/1933Stone et al 28-72 1,966,507 7/1934 Langstreth 242-42 2,311,174 2/1943Hitt 19-66 2,419,320 4/ 1947 Lohrke 28-72 2,811,770 11/1957 Young et al28-72 X 3,145,429 8/1964 Resor 19-157 FOREIGN PATENTS 816,778 7/ 1959Great Britain.

DONALD W. PARKER, Primary Examiner.

1. IN TOW CRIMPING APPARATUS WHICH INCLUDES COOPERATING ROLLS WHICH FORMA NIP FOR ADVANCING A TOW, A CRIMPING CHAMBER BELOW SAID ROLLS FORRECEIVING AND RESTRICTING THE ADVANCE OF SAID TOW, AND A PAIR OF OPPOSEDPLATE MEMBERS HAVING THE INNER SURFACES IN ADJACENT PARALLELRELATIONSHIP WITH THE PERIPHERAL SURFACES OF SAID ROLLS FOR RESTRICTINGTHE LATERAL PASSAGE OF SAID TOW BETWEEN SAID ROLLS: A PAIR OF STATIONARYFLANGED SPOOL GUIDES ADJACENT TO AND IN ADVANCE OF SAID ROLLS, SAIDSPOOL GUIDES HAVING THEIR MAJOR AXES PARALLEL TO THE NIP FORMED BY SAIDROLLS, THE FLANGES OF SAID GUIDES HAVING INWARDLY TAPERING SURFACES WITHTHE BASES OFF SAID FLANGES BEING IN A PLANE ESSENTIALLY PARALLEL TO ANDIN ALIGNMENT WITH THE LATERAL SURFACES OF SAID ROLLS, SAID GUIDES BEINGARRANGED IN STAGGERED RELATIONSHIP WITH THE AXIAL PATH OF ADVANCE OFSAID TOW TO CONTACT OPPOSITE SURFACES OF SAID TOW AND DEFLECT IT FROMITS NORMAL AXIAL PATH AS IT PASSES BETWEEN SAID GUIDES TO SAID ROLLS.